Process for manufacture of high octane naphthas



N0V- 3, 1959 L. A. GORETTA Erm. 2,911,352

PRocEss FOR MANUFACTURE oF HIGH ocTANE NAPHTHAS Filed oct. 31, 1957 Highcfane Gasol/'ne ATTORNEY A tract phase (a portion of which is subjectedto hydrogenative cracking) is essential in obtaining the 100+ UnitedStates Patent O ce r l 2911352 I Patented Nov. 3, 1959 (F-l) octanenumber naphtha. At the same time extraction prior tohydrodesulfurization reduces the hydrogen 2,911,352 requirements forhydrodesulfurization. The raffinate from the solvent extraction step maybe catalytically PROCESS OF HIGH 5 cracked to make more high octanenaphtha for gasoline blendlng, or it may be employed as a very superiorblend- Louis A. Goretta, Hammond, Ind., and Marvin J. Den -ing stock forfuel oils.

Herder, Olymlfia Fields, me aSSigllOrs to Standard Oil Another aspect ofthe present invention concerns an ComPanys Chlcago, ma a c01'P0l'f0lfl0f Indiana integrated process wherein crude oil is fractionated andApplication October 31, 1957, serial No. 693,731 naphtha and gas oilfractions are recovered therefrom.

- The gas oil fraction is then processed in the manner indi- 7 Claims.(Cl. 208-68) cated in the preceding paragraph, i.e. it is catalyticallycracked, unconverted gas oil is solvent extracted, the extract phase ishydrodesulfurized and then fractionated to 'Ihis invention relates to aprocess whereby hydrocar- 15 produce a lower boiling fraction(substantially all of bon oils are catalytically converted to highoctane which boils between about 400 and 600 F.) and a naphthas in highyields. higher boiling fraction, the higher boiling fraction is Aproblem which continuously confronts petroleum catalytically cracked,and the lower boiling fraction is refiners is to produce the highestoctane number naphthas hydrogenatively cracked. The naphtha fractionremoved for blending into high anti-knock gasoline, and at the from thecrude oil is preferably hydrodesulfurized first same time maximizing theyields of such naphthas. and is then catalytically hydroformed toimprove its oc- Various processes such as catalytic cracking of gasoils, tane number and at the same time produce hydrogen. hydroforming ofvirgin and cracked naphthas, hydrode- A hydrogen stream is separatedfrom the products of the sulfurization of oils, and hydrogenation ofoils have been catalytic hydroforming step, and the hydrogen stream isproposed or are in actual use for the production of high employed in thehydrogenative cracking step. A portion octane naphtha fractionsnecessary. of this hydrogen stream from catalytic hydroforming may Anobject of this invention is to provide a combination also be used in thehydrodesulfurization steps. Because' vof refining processes whichproduces naphthas of maxithe activity of the hydrogenative-crackingcatalyst bemum octane number in high yields. A further object is comesreduced when subjected to large amounts of hyto provide acombination ofrefining processes for convertdrogen sulfide and nitrogen compounds, itis important ing gas oil to high octane naphtha fractions in substaninthis integrated process to employ the hydrogen protial yields whilereducing the rates of catalyst deactivation duced from the catalytichydroforming of a hydrodesuland coke deposition thereon that arenormally encounfurized naphtha. After the hydrogen passes through thetered. A further object is to provide an integratedpehydrogenative-cracking unit it may advantageously then troleumreiining process wherein hydrogen is produced be employed in thehydrodesulfurization units. The

.and is used to maximum advantage in reducing the rate makeup hydrogento the hydrodesulfurization units of catalyst deactivation andmaximizing the octane num- (makeup hydrogen is added to compensate forthat which ber of the naphtha fractions produced. Other objects isconsumed in the hydrodesulfurization reaction) is thus and advantages ofthe invention will be apparent from the hydrogen stream which has beenrecovered from the the detailed description thereof. 40 products ofhydrogenative cracking. This latter hydro- In one aspect of the presentinvention, a gas oil is gen stream has a higher HZS content than doesthe hycatalytically cracked to produce a high octane naphtha drogenstream recovered from the products of hydroand unconverted gas oil. Theunconverted gas oil is forming.V In this manner the hydrogen suliidecontent separated from the high octane naphtha and the former within thehydrogenative cracking unit is maintained at is contacted with aselective solvent which preferentially 45 a low level which isbeneficial to the maintenance of high extracts aromatic hydrocarbons. Ahydrocarbon extract activity of the hydrogenative-cracking catalyst.phase rich in aromatic hydrocarbons and a hydrocarbon Figure 1 shows indiagrammatic form an embodiment raffinate phase lean in aromatichydrocarbons is thereby of the present invention whereby components ofcrude oil produced. The hydrocarbon extract phase is then hyareconverted to high octane naphtha fractions in high drodesulfurized bycontact with hydrogen and a catalyst yield. Numerous pumps, heaters, anddetailed features at an elevated temperature. Thereafter thehydrodesulhave been omitted for the purpose of clarity. These furizedextract phase is fractionated into a lower boiling omitted features willbe apparent to those skilled in the fraction, which usually boilsbetween about 400 and 600 art.

F., and a higher boiling fraction. The lower boiling In this embodiment30,000 barrels/day of crude oil is fraction of the hydrodesulfurizedhydrocarbonextract iS charged from source 11 by way of line 12 into acrude hydrogenatively cracked by contacting it at atemperature oilfractitionation system as represented by vessel 13. of about 850 to 1000F. and a pressure of about l000 From fractionating system 13 fixed gasesare removed to 5000 p.s.i.g. with hydrogen and a dual-functioningoverhead by way of line 14; 7,500 barrels/day of a "catalyst havinghydrogenation and cracking properties. naphtha fraction is removed byway of line 16; about A very high octane number naphtha on the order of12,000 barrels/day of a gas oil fraction is removed by 100-1-l (F-l) canthereby be produced. The higher boilway of line 17; and a residual oilis removed from the ing fraction of the hydrodesulfurized hydrocarbonextract bottom by way of line 18. The gas oil, which may boil makes. asuperior charge stock to catalytic cracking. A within the range of about400 or 450 to 900 F. and naphtha having an octane number above 90, e.g.95 F-l above and in the embodiment herein boils within the isproducedtherefrom. By splitting the hydrodesulfur- 65 range of 450 to 750 F., ispassed by way of line 17 into ized extract at about the cut pointindicated and catafurnace 19 wherein it is heated to a temperaturesuitable lytically cracking the higher boiling portion rather than forcatalytic cracking. The heated gas oil is then passed passing the latterto the hydrogenative cracking step, by way of line 21 into a catalyticcracking unit, indicated higher octane products can be produced.Extraction of ,herein as vessel 22. The gas oil is catalytically crackedY-the unconverted gas oil to produce an aromatics-rich exunder usualcracking conditions which may comprise a temperature of 850 to l050 F.,a pressure of 5` to 50 p.s.i.g., a catalyst to oil ratio in the range ofabout 2:1

to 20:1 on a weight basis, a weight space velocity in Vthe y range ofabout 0.2 to 20 pounds of oil per pound of catalyst per hour. Asilaceous cracking catalyst such as natural clay, activated naturalclay, synthetic catalysts such as silica alumina, silica magnesia,silica alumina zirconia, etc. is used. Inthe embodiment shown herein,the gas oil is catalytically cracked using a silica alumina catalyst, atemperature of about 950 F. and a pressure of about 25 p.s.i.g., acatalyst to oil weight ratio of about 10, and a space velocity of about3 pounds of oil per hour per pound of catalyst in the reactor. Aconversion of about 50% of the gasoil to lower boiling products,principally high octane naphtha, is obtained. Any of the various typesof commercial catalytic cracking processes such as uidzed bed, movingbed, fixed bed, etc. may be employed.

The products from the catalytic cracking step are removed and passed byway of line 23 into fractionating system indicated herein asfractionator 24. Light gases are removed from fractionator 24 by way ofline 2.6 and passed to a vapor recovery means, not shown herein, for theremoval of C3 and C., hydrocarbons. A naphtna fraction is removed fromfractionator 24 by way of line 27. It has an octane number ofapproximately 95 or greater, the greater octane number being obtained atconversions of gas oil in excess of 50% or thereabouts. Unconverted gasoil, in the amount of about 6,000 barrels/ day based upon one-passoperation, is removed from fractionator 24 and passed by way of line 28to solvent extraction vessel 29. This unconverted gas oil (commonlycalled catalytic cycle oil) boils within the range of about 400 to 750or 800 F. and has an aromatics content in the neighborhood of about 50%and a rather high sulfur content. Its high content of polycyclicaromatic hydrocarbons makes yit an undesirable catalytic cracking chargestock since it is difficult to crack, gives low gasoline yields andcauses the deposition of large amounts of coke upon the catalyst andleads to more rapid deactivation of the catalyst.

A typical solvent extraction with a solvent which is selective foraromatic hydrocarbons is carried out in extraction vessel 29. Selectivesolvents such as liquid SO2, phenol, cresol, Chlorex, furfural, etc. maybe used in amounts of about 25 to 200 volume precent based upon oil in asolvent extraction process employing one or a considerable number ofstages. In the embodiment shown herein liquid SO2 is employed as theselective solvent at an extraction temperature of about to 25 C., e.g.about C. and under sufficient pressure to maintain the SO2 in the liquidphase. The extraction is carried out in three stages, employing about 50volume percent of liquid SO2 based upon oil in each stage. In theschematic diagram shown in Figure 1 liquid SO2 from source 31 is passedby Way of line 32 into the top of extraction vessel 29. The descendingstream of liquid SO2 passes downwardly through the ascending stream oflighter oil in extraction unit 29 and extracts the aromatic hydrocarbons(as well as considerable amounts of sulfur compounds) from the cycleoil. The raliinate phase which consists primarily of cycle oil, which isnow lean in aromatics, together with some occluded SO2 is removed fromthe top of extraction vessel 29. lt is then passed vby wa-y of line 33into ash drum 34 wherein SO2 is vented from the oil. The SO2 is removedfrom the top of flash drum 34 and passed by way of line 36 into line 37by which it is passed to line 32 for recycle to extraction vessel 29.The hydrocarbon rainate oil, which may vamount to 3,000 barrels/ daybased upon the first pass of oil through the process, is removed fromthe bottom of ash drum 34 by way of line 38 and freed of residual SO2 byequipment not shown. A portion of it may be withdrawn by way of valvedline 39 and used for blending in the manufacture of high quality fueloil. The remainder is passed by way of line 41 to line 17 as a portionof the charge to the catalytic cracking step. This rainate oil is anexcellent charge stock to catalytic cracking. An extract phaseconsisting of liquid SO2 containing dissolved cycle oil which isenriched in aromatic hydrocarbons, is removed from the bottom ofextraction vessel 29 and passed by way of line 42 into flash drum 43.SO2, which is flashed from the extract phase in dash drum 43, is takenoverhead and passed by way of line 44 into line 37 and then is recycledby Way of line 32 to extraction vessel 29. The aromatics-richhydrocarbon extract phase, which boils between about 400 and 750 to 800F. and now has an aromatics content of about is removed from the bottomof flash drum 43, freed from residual SO2 and passed by way of line 46into furnace 47. The cycle oil extract may amount to about 3,000barrels/day based upon the initial pass of crude oil on a once-throughbasis in this embodiment (all iigures presented herein concerningamounts of oil charged to various units and hydrogen consumed thereinare based upon the initial charge of 30,000 barrels/day of crude oilwithout compensation for recycling of streams to various units).

The aromatic-rich hydrocarbon extract phase is heated in furnace 47 toabout the hydrodesulfurization reaction temperature, and is then passedby way of line 48 into hydrodesulfurization unit 49. In thehydrodesulfurization unit, the hydrocarbon extract is contacted with ahydrodesulfurization catalyst at a temperature between about 550 to 850F. with hydrogen in an amount between about. 1000 and 5000 s.c.f. perbarrel of oil at a pressure between about 500 and 2000 p.s.i.g., eg.about 750 to 1500 p.s.i.g., and at a space velocity of about 0.5 to 20volumes of oil per volume of catalyst per hour. Any of the varioushydrodesulfurization catalysts such as the mixed oxides of cobalt andmolybdenum supported on an alumina carrier, molybdena on alumina, nickletungsten sulde, and in general the oxides and/ or suliides of groups 6and/or 8 metals of the periodic table supported upon an alumina-typecarrier may be employed. In the ernbodirnent illustrated herein, thearomatics-rich extract is contacted with approximately 3000 scf. ofhydrogen per barrel of oil at a pressure of about 1000 p.s.i.g. and atemperature of about 750 F. while employing a space velocity of about 5volumes of oil per hour per volume of catalyst. Acobaltoxide-molybdenurn oxide-alumina containing about 3% cobalt oxideand 9% molybdenum oxide is used. Approximately hydrodesulfurization ofthe cycle oil is obtained. Hydrogen consumption is about 1000 sci/barrelof charge to hydrodesulfurization unit 49. Based upon the 3,000 barrelsper day of cycle oil extract obtained in the initial pass of crude oilthrough the process, hydrogen consumption amounts to about three millions.c.f. of hydrogen per day. Additional hydrogen requirements would occurif the cycle oil were not solvent extracted. ln addition to reducing thesulfur content of the cycle oil, some hydrogenation and a slight amountof cracking occurs so that the hydrodesulfurized oil has a somewhatlower boiling point.

The hydrodesulfurized cycle oil extract is passed by way of line 51 intomeans for separating it into various boiling fractions. This means isdepicted here as fractionating tower 52. A hydrogen stream containingsome of the H28 evolved during hydrodesulfurization is taken overheadand passed by way of line 53 into valved line 54 by which it is returnedto line 46 and employed in hydrodesulfurization vessel 49. Naphthaformed during hydrodesulfurization (which may amount to about 10% of thecharge to hydrodesulfurization vessel 49, i.e. about 300 barrels per daybased upon the initial charge of crude oil to the process) is removedfrom fractionating tower 52 and sent by way of line 55 to hydroforrning.A higher boiling fraction, substantially all of which boils above about600 F. and usually boils within the range of about 600 to 750 or 800 F.,is removed from the bottom of fractionator 52 by Way of line 57. Thishigher boiling fraction amounts to about S00 barrels per day based uponthe initial ypass of crude oil through the process. YA portion or all ofit may be withdrawn by way.V of valved line 58 and employed for blendingin fuel oil. Due to its reduced sulfur content and greater stability itforms a valuable component for that purpose. lBecause of its reducedsulfur content and because it has been partially hydrogenated, it may bepassed from line 57 into valved line 59 and then sent to valved line 41by which it may be recycled as a stock suitable for catalytic cracking.

A fraction of the hydrodesulfurized extract, substantially all of whichboils within the range of about 400 to 600 F. is removed fromfractionator 52 by way of line 61. This lower boiling fraction of thehydrodesulfurized extract oilamounts to about 1,900 barrels per daybased upon the initial crude oil passed on a once-through basis throughthe system. This oil is passed into furnace 62 wherein it is heated tothe temperature needed for its .hydrogenative cracking. The heated oilwhich may be at a temperature of about 600 to 900 F. is passed from thefurnace by way of line 63 into hydrogenative cracking unit 64. In vessel64 this lower boiling hydrodesulfurized extract oil is contacted withVhydrogen and a hydrogenative cracking catalyst at a temperature which isin the range of about 850 to l000 F.

The catalyst is a dual-functioning catalyst which combines hydrogenationproperties and cracking. properties so as to cause hydrogenation of theextract oil and thereafter cracking of the oil. The hydrogenationcomponents of such a catalyst may be the oxides and/or sulides of themetals of group 6 and/or 8 of the periodic table (or the metalsthemselves). These are supported .on a carrier having crackingproperties such as natural and activated clays, synthetic catalyticcracking catalysts such as silica alumina, silica magnesia, silicaalumina zirconia, or cracking bases such as HF promoted alumina. Thecatalyst may contain between 1 to 10%, preferably about 5% orthereabouts by weight, of the hydrogenation component supported inextended form upon the cracking component. The catalyst may be preparedby any of the conventional techniques such as by' impregnation of thesupport with an aqueous solution of the hydrogenation component, byprecipitation of the hydrogenation com- 'ponent upon the crackingsupport, or by co-precipitation of the hydrogenation component with thecracking corn- -ponent. For example a silica alumina cracking catalyst"containing between 5 and 20% alumina with the remainder being silica,may be impregnated with a solution of ammonium molybdate, theimpregnated catalyst dried and then calcined to convert the-ammoniummolybdate to molybdenum oxide; thereby producing a catalyst containingabout 5% M003. Other catalysts such as nickle on 'Vsilica alumina, ironon silica alumina, platinum on silica alumina, platinum on uoridedalumina, cobalt molybdate on fluorided alumina, molybdenum oxide onluorided terrana earth, and similar dual-functioning catalyst may beemployed. T his dual-functioning catalyst converts the polycyclicaromatics in the lower boiling extract oil to naphtha by hydrogenatingone ring of the polycyclic, and thereafter by reason of the crackingcomponent of the catalyst this hydrogenated ring is cracked whereuponthe naphtha boiling range monocyclic aromatic is produced. AInhydrogenative cracking vessel 64, the lower boiling ex- `tract oil iscontacted with the dual-functioning catalyst at vthe defined temperature(about 950 F. in this embodiyment) and at a'pressure of about 1000 to5000 p.s.i.g., eg. about 3000 p.s.i.g. while employing hydrogen in theamount of about 2000 to 6000 s.c.f./barrel of feed. A space velocity-offrom 1 to 20, e.g. about 5 volumes of oil per hour per volume ofcatalyst may be used. Conversions to lower boiling products on the orderof 80% 1or higher are obtained, most of it being high octane naphthahaving an antiknock value such as 100 F-l or higher. Omission of theextraction step or the hydrodesulfurization step causes adrasticreduction inthe octane number of the naphtha. Omission of thehydrodesulfurization step also causes a reduction in the extent ofconversion as well as causing an increase in the rate of deactivation ofthe catalyst. Thus these preceding steps are essential. Fractionation ofthe hydrodesulfurized extract so that only the dened lower boilingfraction is charged to hydrogenative cracking is also essential to theproduction of high antiknock naphtha. Because the naphtha produced byhydrogenative cracking of the higher boiling fraction of thehydrodesulfurized extract has been found to have anioctane number of F-lor lower, this higher boiling ,fraction is advantageously processedthrough the catalytic'` cracking unit wherein it yields a naphtha havingan F-l octane number of or higher. In addition, this higher boilingextract fraction is much more resistant to conversionv in thehydrogenative cracking unit. Only about one-third of it is converted tolower boiling products as compared with 80% conversion of the lowerboiling extracts. Its presence in the hydrogenative cracking unit 64would thus `tend to build up. Because increased coke formation isencountered through the use of this higher boiling extract fraction, thedual-functioning catalyst would have to be regenerated more frequently.Approximately l2000 to 2500 s.c.f. of hydrogen per barrel ofhydrodesulfurized extract charged to the hydrogenative cracking unit areconsumed during the reaction. If the higher boiling fraction of theextract were processed through the hydrogenative cracking unit, aninsuicient supply of hydrogen would exist. It would be necessary toemploy generated hydrogen rather than to use the hydrogen which isproduced during the hydroforming of the naphtha fraction. In the processdescribed herein, suicient hydrogen is generated to satisfy the totalrequirements of the integrated reliningA scheme. In this embodimentapproximately four million s.c.'f. ofhydrogen/day (based upon theinitial crude oil on a once-through basis) are consumed in hydrogenativecracking unit 64. To maintain high catalyst activity, the hydrogenstream which is introducedinto vessel 64 is relatively free of H28. Thishydrogen stream is one which is separated from the productsnfromthe'hydroforming of a desulfurized naphtha. The hydrogen 'stream isintroduced by way of line 66 into line 61 by which it eventually reachesthe hydrogenative cracking'vessel 64.

The reaction products from the hydrogenative cracking vessel 64 areremoved therefrom and passed by way of line 67 to a fractionation systemrepresented herein by fractionator 68. Unconverted extract oil isseparated as a bottom stream and passed by way of line 69 back to thehydrogenative cracking vessel 64. The high octane naptha is removed as aside stream and passed by way of line 71 into line 27 where it is laterblended with the other high octane naptha fractions produced to form thehigh octane gasoline. A hydrogen stream is removed overhead by way ofline 72. Because this stream will normally have a higher HZS contentthan the hydrogen stream from hydroforming, it is passed to thehydrodesulfurization vessels wherein it serves as the hydrogen employedtherein. If necessary, a portion of this stream may be recycled to thehydrogenative cracking vessel by way of line 73, but itis preferred notto do so. The major portion of the hydrogen stream owing in line 72 is`diverted and passed by Way of line 74 into line 54 by which it ischarged to hydrodesulfurization vessel 49. The remaining portion of thehydrogen stream is passed by Way of line 75 and is employed in thehydrodesulfurization of the virgin naphtha.

The virgin naphtha removed from the crude oil in frac- ',tionatng system13 is passed by Way of line 16 into furnace 76 wherein it is heated tothe usual hydrodesulfurization temperature. The hydrogen stream in line75 is also heated in the furnace tubes and is passed with the naphtha byway of line 77 into hydrodesulfurization unit 78. In

'silica alumina support, etc.

vof 100 to 400 p.s.i.g.

conditions and with the catalyst employed in hydrodesulfurization unit49, except that a somewhat lower tempera- Ature on the order of about550 to 750 F. is used. Hy-

drogen consumption amounts to about 20 to 60 s.c.f., usually about 40s.c.f. of hydrogen/barrel of naphtha charged. On the basis ofonce-through processing of the initial crude oil, as hereinbefore dened,hydrogen consumption amounts toV about 300,000 s.c.f./day.

The products from hydrodesulfurization vessel 78 are passed by way ofline 79 into fractionation system represented vherein by fractionator81. A recycle hydrogen stream is removed overhead and is returned by wayof line 82 to line 75. The desulfurized naphtha isremoved as a bottomstream from fractionator 81 and passed by way of line 83 through heater84. The small amount of naphtha produced during the hydrodesulfurizationof the cycle oil extract -is passed by way of line 56 into line 83. Theheated naphtha is then passed by way of line 86 into hydro-forming unit87.

In hydroforming unit 87, the octane number of the naphtha is greatlyimproved, e.g., it is increased from about 60 F-l up to 95 F-l orhigher. In the hydroorming reaction, naphthenes are dehydrogenated to-higher octane aromatics and parains are cyclized to aromatcs also. Asubstantial quantity of hydrogen is 'produced per barrel of naphthacharged. This may vary from about 500 to 1200 s.c.f. of hydrogen perbarrel of naphtha charged. The catalysts employed in hydroforming arethose such as molybdena on alumina, chrornia on alumina, and platinumplus halogen on alumina or Of these, it is preferred to employ aplatinum-typecatalyst because it produces the greatest improvement inoctane number of the naphtha and also results in a higher net productionof hydrogen. It is particularly preferred to employ the process known asUltraforming since it produces highest octane numbers and maximumhydrogen production, due in part to its operation at somewhat lowerpressures on the order The hydroforming reaction is carried out bycontacting the naphtha with the catalyst at a temperature of about 850to 1000 F. and a pressure of about 50 to 750 p.s.i.g. A space velocityfrom 0.5 to

` volumes of naphtha/hour/volume of catalyst is used.

Hydrogen is introduced to the reactor at the rate of about 1000 to 6000scf/barrel of naphtha. In the embodiment described herein the naphtha iscontacted with a platinum supported an alumina catalyst containing about1% or even less of platinum at a temperature of about 925 F., a pressureof about 250 p.s.i.g., a space velocity of 1.5, with the introduction ofabout 3-4000 s.c.f. of hydrogen/barrel of naphtha charge. The octanenumber of the naphtha is improved from about 60 to about 98 F-1, and anet production of hydrogen in the neighborhood of about 1000 sci/barrelof naphtha charge is obtained. Based upon the amount charged in thisembodiment, 7.8 million cubic feet of hydrogen/day are produced.

The reaction products from the hydroforming step are passed by way ofline 88 into a fractionating system, indicated herein by fractionatingtower 89, wherein various fractions are separated. High octane naphthais removed from the bottom of fractionator 89 and passed by way of line91 wherein it meets with the other high octane naptha fractions producedin the process. These fractions are blended with additional componentsto form the product high octane gasoline. A hydrogen stream is removedoverhead from fractionator 89 by way of line 92. A portion of thisstream is recycled to the hydroforming lprocess by way of line 92. Theremainder ofthe stream is diverted and passed by way of line 93 to thehydrogenative cracking vessel 64. In startup operations it may jbedesirable to employ some of this hydrogen in the hydrodesulfurizationunits, but thereafter the integrated process functions best by chargingthe net production of hydrogen from the hydroformer directly to thefurnace of the hydrogenative cracking vessel 64.

It is apparent from the foregoing description, that the process of thisinvention provides an integrated system for producing maximum octanenumber naphtha in high yields in an eicient manner which eliminates theneed for using outside hydrogen, and employs hydrogen produced in theintegrated process in a manner which further benefits operation of theprocess.

Thus having described the invention what is claimed l. A process for themanfacture yof high octane naphtha fractions which comprisesfractionating crude oil to produce naphtha and gas oil fractionstherefrom, catalytically hydroforming said naphtha fraction vto improveits octane number and simultaneously producel hydrogen, catalyticallycracking said gas oil fraction to produce high octane naphtha andcatalytic gas oil, solvent extracting said catalytic gas oil to separatean aromatics-rich hydrocarbon extract phase from-an aromatics-leanhydrocarbon ratinate phase, hydrodesulfurizing said hydrocarbon extractphase, splitting the hydrodesulfurized extract phase into a lowerboiling fraction substantially all of which boils below about 600 F. anda higher boiling fraction, catalytically cracking said higher boilingfraction to produce high octane naphtha, hydrogenatively cracking saidlower boiling fraction in the presence of a hydrogen stream recoveredfrom the products of said catalytic hydroforming and in the presence ofa catalyst having hydrogenation and cracking properties to produce ahigh octane naphtha.

2. The process of claim l wherein a hydrogen stream is separated fromthe products of the hydrodesulfurization step and recycled thereto, andthe makeup hydrogen which is supplied to said hydrodesulfurization stepis a hydrogen stream separated from the products of the hydrogenativecracking step.

3. The process of claim 1 wherein the naphtha produced during saidhydrodesulfurization step is passed to said hydroforming step.

4. A process for producing high octane gasoline boiling rangehydrocarbons which comprises catalytically cracking a gas oil to producehigh octane naphtha and catalytic gas oil, extracting said catalytic gasoil with a solvent which preferentially extracts aromatic hydrocarbonsand thereby producing a hydrocarbon extract phase rich in aromatichydrocarbons and a hydrocarbon raffinate phase lean in aromatichydrocarbons, hydrodesulfurizing said hydrocarbon extract phase,splitting said hydrodesulfurized hydrocarbon extract phase into a lowerboiling fraction and a higher boiling fraction, `hydrogenativelycracking said lower boiling fraction by contacting it with a catalysthaving hydrogenation and cracking properties in the presence of hydrogenand at a temperature of about 850 to 1000 F. and thereby producing ahigh octane naphtha.

5. The process of claim 4 wherein substantially all of said lowerboiling hydrodesulfurized extract fraction boils between about 400 and600 F., and wherein said higher boiling hydrodesulfurized extract iscatalytically cracked.

6. A process for the manufacture of high octane naphtha fractions whichcomprises fractionating crude oil to produce naphtha and gas oilfractions therefrom, hydrodesulfurizing said naphtha fraction andthereafter hydroforming said hydrodesulfurized naphtha fraction toimprove its octane number and simultaneously produce hydrogen,catalytically cracking said gas oil fraction to produce high octanenaphtha and catalytic gas oil, solvent extracting said catalytic gas oilto separate an aromaticsrich hydrocarbon extract phase from anaromatics-lean hydrocarbon raflinate phase, charging said hydrocarbonrailinate phase to the catalytic cracking step, hydrodesulfurizing saidhydrocarbon extract phase, splitting the hydrodesulfurized extract phaseinto a lower boiling of about 400 to 600 F. and a higher boilingfraction substantiall al1 of which boils above about 600 F., chargingsaid higher boiling fraction to said catalytic cracking step,hydrogenatively cracking said lower boiling 'fraction at a temperaturebetween about 850 to 1000 F., a pressure between about 1000 and 5000p.s.i.g. in the presence of hydrogen anda catalyst having hydrogenationand cracking properties and lthereby producing high octane naphtha,recovering a hydrogen stream from the productsof the hydroforming stepand charging said hydrogen stream to the hydrogenative cracking step,recovering a second hydrogen stream from the products of thehydrogenative cracking step and charging portions of said secondhydrogen stream to the hydrodesulfurization steps.

7. The process of claim 6 wherein said hydroforming step employs asupported platinum catalyst, an operating temperature of about 850 tol000 F. and a pressure of about 50 to 400 p.s.i.g.

References Cited in the file of this patent UNITED STATES PATENTSLaughlin Oct. 22, 1946 2,608,470 Helmers et a1. Aug. 26, 1952 2,703,308Oblad et al Mar. 1, 1955 2,769,753 Hutchings et a1 Nov. 6, 1956

1. A PROCESS FOR THE MANUFACTURE OF HIGH OCTANE NAPHTHA FRACTIONS WHICHCOMPRISES FRACTIONATING CRUDE OIL TO PRODUCE NAPHTHA AND GAS OILFRACTIONS THEREFROM, CATALYTICALLY HYDROFORMNG SAID NAPHTHA FRACTION TOIMPROVE ITS OCTANE NUMBER AND SIMULTANEOUSLY PRODUCE HYDROGEN,CATALYTICALLY CRACKING SAID GAS OIL FRACTION TO PRODUCE HIGH OCTANENAPHTHA AND CATALYTIC GAS OIL, SOLVENT EXTRACTING SAID CATALYTIC GAS OILTO SEPARATE AN AROMATICS-RICH-HYDROCARBON EXTRACT PHASE FROM ANAROMATIC-LEAN HYDROCARBON RAFFINATE PHASE, HYDRODESULFURIZING SAIDHYDROCARBON EXTRACT PHASE, SPLITTING THE HYDRODESULFURIZED EXTRACT PHASEINTO A LOWER BOILING FRACTION SUBSTANTIALLY ALL OF WHICH BOILS BELOWABOUT 600*F. ANDA HIGHER BOILING FRACTION, CATALYTICALLY CRACKING SAIDHIGHER BOILING FRACTION TO PRODUCE HIGH OCTANE NAPHTHA, HYDROGENATIVELYCRACKING SAID LOWER BOILING FRACTION IN THE PRESENCE OF A HYDROGENSTREAM RECOVERED FROM THE PRODUCTS OF SAID CATALYTIC HYDROFORMING AND INTHE PRESENCE OF A CATALYST HAVING HYDROGENATION AND CRACKING PROPERTIESTO PRODUCE A HGH OCTANE NAPHTHA.